Clock and Watch Work; From the Eighth Edition of the Encyclopaedia Brittanica

Clock and Watch Work; From the Eighth Edition of the Encyclopaedia Brittanica

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1855 edition. Excerpt: ...F also then reaches the tail of the backward click CF; so that while things are in this state, the wheel cannot go forward without pulling the lever out of contact with the magnet, which no wind would be strong enough to do while it remains a magnet; and as soon as the circuit is broken, the lever ought to go and will go, being pulled down by the weight W, till it rests on the lower banking pin E; and in so doing, the click A will drive the wheel forward one tooth, and the click DG will drop into the space next after the tooth G, and be pressed back against its spring till it is lilted again by the lever. Another advantage of this plan over those in which the magnet drives die wheel directly is, that the weight is always ready to pull down the lever as soon as the current ceases; so that if there should be any momentary impediment from residual magnetism or otherwise, it will not signify; and, moreover, the wind can never prevent the lever from being lifted; and if there should be any resistance to the hands from wind at the moment when the current ceases, the weight is sure to have the opportunity of overcoming it before the next 29 seconds are over; so that a whole move of the hands can never be lost, which has always been liable to happen under the other arrangement in large dials. There is no such difficulty in making the half-minute contact as there is in seconds contact, because plenty of time can always be taken for it; and it may be done by a slower wheel in the train, and therefore not so liable to affect the force on the pendulum. As the third wheel in the train generally turns in 7 minutes, there may be 15 pins in it pressing a spring which makes contact, or raising a lever or a spring which drops on to a plate. Where the gravity...show more

Product details

  • Paperback | 60 pages
  • 189 x 246 x 3mm | 127g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236538080
  • 9781236538086